A Preparation Method Of Aerogel-expanded Perlite And Its Application In The Concrete

Silica aerogel is a kind of nano-scale thermal insulation material with lightweight and low coefficient of thermal conductivity. It is widely paid attention forits excellent insulation performance,and used in aviation and other high-techfields.But due to the complexity of its preparation technology,preparing productswith low intensity is expensive,which is severely limit to its application in thefield of architecture. How to improve the strength of silica aerogel products atthe same time, reduce the preparation cost which make it can be widely used inconstruction field needs is the key to solve problems.Expanded perlite which is widely used in the field of construction havefeatures of low cost, good fireproof, high strength, low coefficient of thermalconductivity. Current building energy efficiency and fire preventionrequirements for building wall insulation put forward higher requirements. Andexpanded perlite as main insulation aggregate of inorganic heat preservationmaterial,its rate of closed hole is the key indicators that influence its coefficient of thermal conductivity. There is a big randomness during the process ofexpansion.It is extremely difficult to reduce the rate of obturator and reduce thecoefficient of thermal conductivity. Guaranteeing the strength of expandedperlite and controlling its application cost at the same time, and reducing itsthermal conductivity is the key point of sustainable development in the field ofbuilding energy efficiency.In this article, cheap expanded perlite as the carrier, the silica aerogel willbe sucked into the expanded perlite, forming a new type of composite insulationmaterial, aerogel-expanded perlite. aerogel-expanded perlite is convenient tocontrol materials price at the same time, the complementary advantages of twokinds of material. On the one hand, using expanded perlite as silica aerogelenclosure can improve the strength of silica aerogel; On the other hand, silicaaerogel filled with expanded perlite cavity, can reduce the expanded perlite,thermal conductivity and avoid bottleneck expanded perlite processimprovement.In this paper, it is based on the above goal, and do the following research:(1) The preparation of silica aerogel.This paper choose the sol-gel method to prepare silica aerogel. We studiedthe dosage of each raw material and three methods of hydrophobic treatmentregularity influencing on the properties of silica aerogel products using a varietyof micro means for the indicators to measure the performance ofcharacterization of the finished product. We comprehensively considered the microstructure characteristics of silica aerogel products, hydrophobic propertyand thermal stability, obtained the optimum mixture ratio of silica aerogel,optimal hydrophobic process.(2) The preparation of aerogel-expanded perlite.This paper adopts the vacuum impregnation adsorption technology to makesilica aerogel inhaled into the expanded perlite to prepare compositeaerogel-expanded perlite. We studied the different size range of expanded perlitecarrier and a kind of size range GHB(Glass Hollow Beads) carrier on effect onthe properties of aerogel-expanded perlite products. The characterization ofaerogel-expanded perlite products by micro means the indicators (specificsurface area, thermal stability, thermal conductivity) were determined, incombination with aerogel-expanded perlite microstructure and chemicalcomposition, obtained the best carrier particle size range.(3) Application research of aerogel-expanded perlite in the concreteBased on the GHB insulation bearing C30concrete foundation formula,we use aerogel-expanded perlite as insulation aggregate used in concrete, andtest the cube compressive strength and thermal conductivity, The comparisonand analysis result conclude that aerogel-expanded perlite coefficient of thermalconductivity of aerogel-expanded perlite concrete is lower than the GHBinsulation concrete and expanded perlite insulation concrete, and far below theordinary C30concrete. At the same time, it proved that nanometer modificationcan effectively reduce the thermal conductivity of concrete through reasonable insulation aggregate.